Spring, before new growth begins, or fall, after the first frost are the least disruptive times to move a butterfly bush. You can move it now, but it will be easier to move if the top growth is removed and if you cut it down now it will try to regrow. Anything that grows will die down with the first frost. While this won't hurt the plant, it could sap its energy and it will be slower to grow and leaf out next spring. Just a few things to know before tackling the move. Aside from the above, there's not much to keep in mind when moving a butterfly bush. Water it well after the move to help the soil settle and keep it watered regularly to encourage re-establishment of the root system. Best wishes with the move.